Many wireless communication standards use block codes, such as turbo codes, to increase the performance of channel decoding. In block coding techniques, the encoding and decoding processes are done on a block-by-block basis. Many standards, such as WiBro, CDMA2000 and WCDMA, use turbo encoding and decoding functions that handle different block sizes, spanning from a few bits to 20 kilobits (e.g., CDMA2000).
The performance of a channel decoder is significantly impacted by the stopping criteria used to halt execution of the decoding algorithm. A considerable amount of literature discusses stopping criteria for binary data turbo decoding. Some conventional binary data standards (e.g., WCDMA) have stopping criteria based on the mean and/or minimum log-likelihood values. Other binary data stopping criteria use a threshold value for the log-likelihood which must be reached by a pre-defined fraction of the binary data.
Prior art references also discuss stopping criteria for duobinary turbo decoding. Some duobinary systems (e.g., WiBro) implement a stopping criterion based on the consistency of the decoded hard bits. Other duobinary stopping criteria are based on the values of the forward state metric.
However, there is no literature available on unified stopping criteria for reconfigurable wireless communication devices (e.g., software-defined radio (SDR) systems) that are capable of both binary and duobinary turbo decoding.
Therefore, there is a need in the art for an improved reconfigurable decoder for use in a software-defined radio (SDR) system. In particular, there is a need for a unified stopping criteria that may be used by a reconfigurable decoder to terminate the decoding of either binary data (e.g., WCDMA mode) or duobinary data (e.g., WiBro data).